The present invention relates to an escalator and more particularly to an improvement in the steps of an escalator.
In FIGS. 1 to 6 of the attached drawings there is shown an example of typical conventional escalator steps. In FIG. 1, the reference numeral 1 indicates an escalator, having steps 2 to transfer a passenger 3 thereon. A number of steps 2 are connected together by a linkage (not shown) at a definite pitch p (usually about 400 mm) in an endless fashion such that the treads 21 of adjoining steps 2 lie together so as to be aligned with each other in a plane at locations c and c' constituting upper and lower landing portions 4 and 4', and so that steps 2 move in a stair-like fashion between the landing portions. Steps 2 are shown in detail in FIGS. 2 to 4 and 6. The tread 21 for carrying a passenger usually has a width W of 600 to 1,000 mm, a number of cleats 211 having a thickness T1 (usually about 3 mm), and grooves 212 alternately disposed thereon at a definite pitch P1 (usually about 9 mm). The forward ends 213 of the cleats 211 project beyond grooves 212 a definite distance L1 (usually about 6 mm). A convex riser 22 is provided at the rear end of tread 21 so as to form substantially an L-shaped configuration therewith, and has a number of cleats 221 each having a definite thickness T1 and grooves 222 alternately disposed on the convex surface at a definite pitch P1 the same as that of cleats 211 of tread 21. The forward ends 213 of cleats 211 on tread 21 of the step directly behind any given step are adapted to be engaged in grooves 222 in riser 22. Brackets 23 integrally connect tread 21 with riser 22, and rollers 24 are mounted on axles 25 on brackets 23, the rollers 24 being adapted to roll on guide rails (not shown) by connecting axles 25 to linkages not shown.
When steps 2 are connected together in an endless fashion and moved in the direction shown by the arrow A in FIG. 1, i.e. when escalator 1 is operated upwards, at the time steps 2 pass through the region between points B and C shown in FIG. 1, step 2 moves, as shown in FIG. 5, stepwise relative to preceeding step 2' in the direction represented by the arrow D from a position E through a position F to a position G where the tread thereof is level with the tread on the preceding step 2'. In this case, should a passenger 3 carried on step 2 strongly thrust the toe 32 of his footwear 31 against cleats 211 of riser 22 of preceeding step 21, toe 32 is forcibly bent downwards due to friction with the riser 22, particularly when the footwear 31 is made of rubber which has a relatively large coefficient of friction, and when step 2 reaches position G, i.e. a level state, since there is usually a gap 26 of width H of 3 to 5 mm left extending across the whole width of steps 2 and 2' between forward ends 213 of cleats 211 of tread 21 of step 2 and the rear ends of cleats 211 of tread 21 of preceeding step 2', there arise disadvantages such that toe 32 of footwear 31 can become caught in the gap 26 formed between adjacent steps 2 and 2', i.e. between forward ends 213 of cleats 211 of tread 21 of step 2 and the rear ends of cleats 211 of tread 21 of preceeding step 2', or long bar-like foreign objects are apt to fall through gap 26, and if the foreign objects are made of hard metal or plastic they may cause damage to the mechanical parts of escalator 1 due to being thrust into the upper and lower landing portions 4.
FIGS. 7 to 11 show another example of conventional escalator steps wherein the forward ends 213 of alternate cleats 211 of tread 21 project a distance L1 while the rear ends of these same cleats 211 which have projecting forward ends 213 are shortened such that the rear ends 213' of these cleats 211 are aligned with the bottom faces of grooves 222 in riser 22 each having a depth of L1, and the rear ends 214' of cleats 214 which do not have projecting forward ends project by a distance L1 together with portions of the adjoining grooves so as to have a width T2, whereby riser 22 has cleats 221 each having a height L1 and a width T2 aligned with rear ends 214' of cleats 214 of the tread 21.
Thus, in this example pitch P2 of cleats 221 and grooves 222 in riser 22 is double the pitch P1 in the first example, width T2 of cleat 221 being 1 to 4 times the width T1 of the cleat in the first example. (In the example shown this is about 3.5 times.)
In the case where an escalator provided with steps having such a construction is operated to move upwards, as shown in FIGS. 10 and 11, irrespective of whether the treads of adjoining steps 2 and 2' are in a stair-like state as represented at positions E and F, or they are aligned in a horizontal state as shown at position G, the forward ends 213 of cleats 211 of tread 21 of step 2 are engaged in grooves 222 of riser 22 of the preceeding step 2' of indented portions of tread 21 thereof at the rear end thereof which are in communication with grooves 222. Therefore, even when the treads of steps 2 and 2' are aligned in a horizontal state as shown at G in FIG. 10, the forward ends 213 of cleats 211 of tread 21 of step 2, as shown in FIG. 11, engage rear ends 213' of cleats 211 of tread 21 of preceeding step 2' (including also portions of adjoining grooves 222) to a depth J so that there is no linear gap 26 as in the first example, preventing the occurrance of footwear or long foreign objects being caught between the confronting ends of adjacent steps 2 and 2' as in the first example. However, on the other hand, when steps 2 are in a stair-like state in the region between points B and B' shown in FIG. 1, the length S of gap 27 formed between adjacent projecting ends 213 of cleats 211 of tread 21, gap 27 having a clearance H of 3 to 5 mm between the confronting forward end 214 of cleat 211 of tread 21 of step 2 and rear end 214' of cleat 211 of tread 21 of the preceeding step, becomes larger than the corresponding length in the first example so that coarse dirt is apt to fall through gap 27 formed between two adjacent steps 2 and 2' and be caught in the interior of the escalator, possibly causing its breakdown.